The present invention relates to a damper assembly associated to a torque converter of an automobile or the like.
Generally, in a torque converter itself, there is essentially a power loss owing to slip in operation liquid, resulting in bad fuel consumption. Therefore, lock-up clutches or direct coupling mechanisms have already been assembled in some torque converters. In these torque converters of the direct coupling type, an output part of an engine is directly connected through said mechanism to a transmission in the direct coupling operation. Therefore, vibration and shock of a torque generated in the engine during speed-changing operation and accelerating operation are directly transmitted to the transmission, which causes gear attacking noises and other noises. Further, in some of the torque converters provided with the lock-up clutches or direct coupling mechanisms, drag of insufficient disengagement may be caused in a hydraulic clutch part in the transmission in the idling driving, which also results in the gear attacking noises owing to the torque vibration in the engine.
In order to absorb such vibration, it has been proposed to use dampers having large maximum torsion angles, as described in the Japanese Patent Application No. 57-10387 (U.S. Pat. No. 4,493,674; German Patent Application No. P 33 02 536. 3) and the Japanese Patent Application No. 56-174726 (U.S. patent application Ser. No. 436,804; German Patent Application No. P 32 40 238. 4). The structures of said Japanese Patent Application No. 57-10387 include a plurality of springs arranged in series with floating members such as equalizers and free spacers therebetween, and has twisting or torsion characteristics, which are symmetrical and same in positive and negative directions. However, as a result of tests in which those dampers were equipped in actual automobiles, it was proved that the conventional dampers can not sufficiently absorb the torque vibration, especially at an area of low torsional rigidity, i.e., during the idling driving.